The present invention relates to the field of respirator cartridges. More particularly, the present invention relates to a prefilter system comprised of two circular filter elements positioned in a snap-on housing. The prefilter system comprises a fiberglass filter element which is perforated by sixty-four Pins and is adhesively bonded to a felt filter element. The Perforation of the fiberglass filter breaks up and fractures the binder used in the manufacture of the fiberglass. This allows a contaminant to penetrate into the body of the prefilter. The filter housing snaps onto the chemical cartridge of a respirator or gas mask.
Filter elements which clip or snap onto chemical cartridges of gas masks are well known. Unfortunately, such prior art filters suffer from premature clogging. This clogging results from dust and other particulate matter caking on the surface of the filter. The clogging problem is exacerbated in a dusty environment. When large amounts of dust or particles are present, the filter cake forms at a rapid rate, to a point in which the filter is no longer functional. Moreover, because the prior art filters are flat on their outer surface (the surface on which the cake forms) most of the filter is never used before the filter loses its functionality.